Valentine's Brood
by Pen-Always-In-Hand
Summary: Jonathon/Sebastian ponders on his connections to Jace and Clary, how he 'loves' them, and the things he would 'let them get away with'.
1. Pondering Demon

**A.N-Okay, this story stems from three things: a strange and sort of sick fascination with Clary/Jonathon things that has started growing recently, a desparate want to know what happened between Jace and Jonathon, AND the excerpt from City of Lost Souls on Cassandra Clare's webpage. Um, I guess you don't really need to read that for this, but it would help for a few things.**

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><p>"Go ahead," he said, leaning against the fountain. "I don't mind watching."<p>

As he watched them move away, walking, dancing, kissing, he thought how interesting their relationships with each other were. Clary-what a disgusting nickname, for something so fine and elegant as _Clarissa_-was his sister, but he felt more of a connection to Jace (but he was Jace's master, bound to each other by blood and acceptance). Of course, Clary-(how he hated that name. He would call her Rissa from now on)-Rissa in a way was also Jace's sister, though she would screech and rant to high heaven that they were in no way related, and Jace would freak out and deny it with his dying breath. But they would be wrong (on two accounts, the first being he and Jace were _one, _and if he was Rissa's brother, where did that leave Jace?) The second was this: Didn't they both have extra angel blood? Didn't it come from the same angel (Ithuriel)?

But even though they were angels, they were on the verge of falling. For how could they _not _be on the outside of grace, in their situation? Because of _his _lies, they had sinned before God and man. And, Rissa had _his _blood, and Jace had _his _training. And, of course, he had both, and all of Idris had felt what a dangerous combination that was. Yes, Rissa would always be a Morgenstern, no matter what last name she hid behind. And Jace, always _his _son, brought up with _his _views, even though he lived with the Lightwoods now. They would always be his younger siblings.

She, his sister by blood.

He, his brother by adoption.

As he watched them, he was awestruck by by the golden aura enveloping the two. A pure, holy yellow that was the closest thing he would ever get to Heaven. He longed to touch it, _them, _to cover himself with this vibrant thing that pulsed with life and gleamed with beauty. But what was that he saw? A black stain on Rissa's aura, sometimes flaring red-with what (anger passion embarrassment)?-and then changing back to black. Ah, of course: only _his _daughter could have such a dark heart . A torrent of orange-red flickered through Jace's soul, but that wasn't so disturbing.

Jace was hard and Jace was tough, but he was also very broken, and he looked to them to heal him. Rissa, however, was strong and cruel and powerful, try as she might to deny it. Her soul, while seemingly so inviting, was really a cold, dark, hellish pit. How he would love to rip her off her throne of superiority and throw the truth in her face! He wanted to shake her and make her _see. _He wanted to beat her and make her _cry. _He wanted to scratch her and make her _bleed, _and he wanted to laugh at her pain, because it was _so hilarious _that someone like her would let herself be beaten by someone like him. Now _she _was a Morgenstern, thick and arrogant, though still untrained.

But, she was still his sister. He had to protect her. Only her brothers were allowed to hurt her; anyone else who did that to his Rissa would pay. He would go after them with a giddy, blood-thirsty vengence. Because, connected as they were by varying degrees of blood (demon blood, angel blood, biological blood), they could do whatever they wanted to each other. If Jace wanted to rip Rissa's heart out and stomp on it, he wouldn't stop him. If Rissa wanted to tear Jace's soul to shreds, that was alright. And if they ever wanted to leave him, he would let them go (but they wouldn't: Jace was in union with him, and Rissa would never leave Jace, and so would stay with him) because they were the only ones who could hurt him with impudence, and the only ones he could love with sincerety.

He supposed he craved their companionship, their trust. What had he done to deserve it? Nothing. But he felt like it was his right, to be trusted by his siblings. He loved them, truly, in the only way a demon can: wanting them near him, wanting to see them all the time. Sometimes, however, he grew dangerously jealous of their love. He wanted to do something that would ruin their trust in each other forever. But then they really would hate him, and he didn't want that. He wanted their trust, their friendship, their love. Why?

Because it could get lonely down in Hell.

Because demons were angels once, too.


	2. Weeping Angel

Clary didn't know what to do. She felt alone-she _was _alone, no one else was in the apartment: her mother and stepfather were out for lunch, and Jace was doing only God-knew-what. Isabelle had accompanied Alec and Mayrse to Idris to see their father, and Magnus was also doing God-knew-what.

So she was alone.

With only evil memories.

Of a cruel and sinful day.

But someone _had _been here not that long ago, someone who had put his hands on her and his tongue in her mouth and his words in her ear-something she couldn't tell anyone about, because the one other person who knew about his existance was too friendly, too _infatuated_ with him that he would probably never believe her. Then again, he might, and she would most likely be rid of the person, but she knew the ensuing battle (because what else did Jace wager? Certainly not _fights_, _definitely_ not brawls) would be ugly and costly.

Oh, don't you know? Don't you know that neither Jace nor she had told anyone about **his **resurrection, that **he **was walking around, assaulting and scheming and walking and breathing and _living, _when he had no right to? though Clary was glad he had a right to, because Jace had one too because of it -she couldn't live without Jace, and now living _with _Jace included **him. **Oh, how she hated **him.**

Oh, right, you still don't know. You don't know that the monster is Jonathon. You don't know Lilith's beloved son is Jace's new companion.

You don't know, Clary's new worst nightmare, is her own brother.

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><p><em>It was a dark, rainy day. Of course, the aforementioned people were doing the aforementioned things (whatever things Jace and Magnus were doing), but today Clary had felt like being alone. She just wanted to go inside and draw: she wanted to put pen to paper and shape a body for the images in her mind, to turn imagination into reality.<em>

_But that plan was interrupted by a blond-haired demon. When she opened the door, she nearly had a heart attack, seeing **him** sitting in the recliner, flipping through one of _her _sketch pads. She had felt a flash of irritation, and wished **him** gone immediately. She had felt relieved, though, that her parents weren't home (though **he **probably already knew that). She had stalked right up to **him** and yanked her drawings from **his** hand-except one tore out (perfectly though) and she realized **he **had already neatly removed the drawing from the book. It was her latest one, one that had been inspired by her two angels-one golden and alive, the other dark and fallen. _

_One couldn't tell, of course, that it was based on Jace and Jonathon: it merely showed a warrior (a Nephilim) in Shadowhunter gear, with a seraph blade in each hand. The warrior's hair was blond, but that's were it got odd and fantastic and something that could only come out of the mind of one with Heavenly origins. Sprouting from his back were two brilliant wings, spreading out and filling up the page. The right was gold; the left: black. Coincidentally (or maybe not, probably not, most definitely not) the right eye was a leon yellow, and the left eye was a soul-wrenching black. And finally, were the changes. The right and left sides of the face were slightly different, the changes unperceptible to the untrained eye, such as that of Luke (Jocelyn had caught it, had recognized, had been disturbed by it). The left side was more angular, crueler in its features, while the right was softer, with low cheekbones and a slightly round finish to it. _

_If Jonathon and Jace were dressed in monster-hunting gear, with a blade in their hands and were put side-by-side (as they often were, nowadays), you would get her drawing, minus the wings._

_"Lovely representation," **he** purred, rising from the chair, lithe as a cat-or maybe the lion Jace so remined Clary of sometimes. If Jace was lion, then Jonathon was a panther-dark, different, but just as dangerous. "I especially liked the wings. A fitting touch, no?"_

_"What do you want, Jonathon?" Clary asked, exasperated with **him** already. She knew what _she _wanted: she wanted **him** gone, so she could draw in peace. **He** was disturbing her peace. There should be some law against that (wasn't there one?) though her brother _(insert wince) _most likely wouldn't care._

_"What do I want? Well, Rissa, that is an interesting question." _Rissa?_** He** had never called her that before, though she knew **he** hated her nickname, and she supposed 'rissa' was a good abbrevation for 'clarissa', but it just made her more annoyed._

_But that annoyance soon dissipated, replaced with fear and shock and bewilderment. Because, no sooner had **he** spoken than **he** had her pressed against the wall, one arm pinning hers and one knee rammed against her other palm, keeping her prisoner between **his** cold body and the colder wall._

_"What do I want? I want to know what those lips taste like, free of decpetion and distraction." And, so quick (so so quick/like Jace but almost faster/how was he that fast/she knew why/didn't want to), **his** mouth was on hers, crushing, moving, trying to get inside. But she wouldn't let **him** Oh no, no no no._

_**He** was strong, and almost all **his** weight was leaning on her. Jace's training had so far only covered flips and surviving bruises and running away; they hadn't gotten to building up her muscle so what was she against demon strenth (inherited from the Mother no less)? She struggled, of course, mightily, but **he** was determined to taste her (**he** tasted like chocolate and tears and death) and her attempts were futile._

_And then, she didn't know why; maybe it was the slow loosening of **his** grip, or the way **his** taste morphed into something sweeter-_vanilla and strawberries_-or_ something _but she thought he was Jace, and Jace was him, and she opened her mouth (just a little, only a slight partng of her lips) but **he** immediately slipped in. But as soon as **his** tongue started to tangle with hers, she _REMEMBERED. _She remembered that **he **_wasn't _Jace and how could she be so stupid Oh God Oh Angel what was she going to do. _

_She finally realized what she could do: bite **his** tongue._

_Blood welled up in her mouth, but it wasn't hers. It was coppery and sweet, and she heard **him** make a surprised noise but **he** didn't pull back. Instead, **he** seemed to enjoy it, but the taste made her sick. And then she realized: another thing, a perfect thing, a fitting thing to save herself._

_She kicked **him** in the grion_

_gulped in a deep breath when **he** jerked away_

_and spat out **his** _blood_ and **his** _taste_ and **his** _sin_._

_The sound of his laughter infuriated her, and _now_ she could reach the seraph blade in her pocket. She took it out and, without naming it, without precision or calculation or thought, threw it at **him** with all she had. **He** raised **his** arm to block it instead of dodging like she knew **he** could. The blade bit through flesh, and scarlet stained the skin, and still **he** laughed._

_"Only you, Rissa; only you." And then **he** raised the wound to **his** mouth and licked it clean. Then, so fast she couldn't catch it, **he** disappeared, the creak of the door hinges the only indication it had been used._

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><p>And so she had curled into a ball to cry. She cried and sobbed and wept, and still no one heard her, because she did it quietly, as if her brother's sin was now her shame to be covered.<p>

She cried because she had been violated;

she sobbed because she had been helpless;

she wept because she had confused an angel with a demon.

And she did so quietly, so know no one would ever know.


	3. Raging God

"Sebastian!"

Jace knew his foster brother rather hated that name - a pseudonym, an alias, a stolen name from a murdered child. Jace, frankly, didn't care. However, as time wore on, he found himself refering to Lilith's son as 'Jonathon', the name they had shared for seventeen years. (Jace knew that Clary was the only one who called her brother Jonathon, while Isabelle and Alec called him Sebastian, refusing to admit a connection between their brother and their brother's killer.) But when Jace called him _Sebastian, _they both know he was angry.

And Jace was ballistic.

He was furious with his brother, who was Clary's brother (did he not care they were related, that she was taken, perfectly happy?) Maybe Clary was right and he was only a demon, with nothing in that black heart of his. But Jace _knew _Sebastian's heart. Jace's heart was Sebastian's heart; the proof of that was painted on his chest in the shape of a child's hand.

Maybe Sebastian just wanted his heart back. If he could, Jace would have gladly given it to him, but Sebastian's heart was Jace's heart, and he had given it to Clary.

"Sebastian, you motherf***er, get down here!"

"I do believe you mean _sister_ f***er. Of course, it didn't get quite that far, I can assure you." Jace whirled around to see Sebastian standing on one of the rafters. Jace saw red for a minute, and then he was lunging at the demon-boy, all ready to choke the life out of him, to see the light dim in his lecherous eyes. Jace wanted to stab him through the spine again. He wanted to dismember him, castrate him, gouge his eyes out, take off his _other_ hand, along with the arms.

But Sebastian had the same gifts Jace did, and so they entered into a deadly dance, a murderous game of wiles and wounds. Sebastian was sure he would win, for though Jace's skills matched his, Sebastian still had a clear head - and that would make all the difference.

"Did she cry when she told you?" Sebastian mocked. "Or was she angry? I bet she was ashamed - why else wait so long before telling you?" Jace couldn't respond, just howled in rage as he pounced on his foster brother, dodging a blade, blocking a fist. The older boy's words were more infuriating in part because they were also true. Clary _had_ cried when she told him, she _had_ been ashamed. There was no anger, just a crushing sadness; he had been furious enough for the both of them.

_He smiled at her, and she smiled tenatively back. He traced her lips with his finger, and she gasped. Slowly, he put his hands on each side of her head and brought her face to his._

Jace grunted as Sebastian's knee hit him in the gut. Before going out he had insisted Alec put a Numb rune on him, which would dull a little of the pain he knew would come with a fight with his brother. It wasn't like Clary's Fearless rune (what was?) but it was the best his parabatai could do. Alec had tried to insist on coming, but Jace wouldn't hear of it - partly because Alec still didn't know about Jonathon/Sebastian. But that was just it - the matter was private, just for the three of them: Jace, Clary, and Sebastian.

Jace lashed out and caught Sebastian on the cheek with his nails. The demon-boy pulled back, surprised at such a dishonorable hit. But Jace wasn't fighting for his honor. He was fighting for Clary's.

_"Stop!" she cried. He froze, his lips inches away from hers. What was wrong? What had he done? His alarm grew as he saw tears gather in her eyes._

_"Jace...Jace I'm sorry, I'm just-"_

_"Clary, what's wrong? What am I doing? You've been like this for a while - if I hurt you, or insulted you, you need to tell me-"_

_"Oh, no, not **you**, Jace! Not you," she exclaimed, eyes going wide. She looked lost, hurt. As if she didn't know who to turn to. "It's just - it's just...he...he..." and the tears ran down her cheeks._

"I'm going to kill you," Jace growled. Their fight was going nowhere; it was a stalemate. Jace wanted to knock that sinister smile off those unholy lips but he knew his words were almost akin to an empty threat.

_An angry, alarmed buzzing sounded in his head._

"I'm not going anywhere you aren't," Sebastian answered as he pivoted out of the way. "Do you know I watched you? That night at the club, when you two danced the night away?" Jace growled and started throwing punches, not caring where they landed as long as it was on him. Jace's eyes widened as Sebastian's voice sounded right near his ear,

"She belongs to both of us, you know. You two are a perfect match, but she's still mine. She and I are the very last of the Morgensterns - she is the only one who shares the same blood as me. Every. Single. Drop."

"Not every drop," Jace hissed as he spun around.

_"He's a demon - I've told you over and over Jace. A demon; he has no heart," Clary whispered. She shook her head but did not resist him when he gathered her in his arms. He pressed his lips against her hair._

_"What happened, Clary? Please, please, **please** tell me. Maybe I can help."_

_"You're too late - it's already done."_

"Mmm, that's true, isn't it? She has angel blood whereas I'm full of evil." Sebastian laughed, then winced as Jace's blade (Raphael) sliced his arm. He growled and lunged, ripping at Jace's shoulder in retaliation. "Did she ever tell you that's not the first time our lips were together? Did you know we've kissed before - with mutual consent, that I can promise you."

_She sobbed out her story, and Jace's heart constricted. _How dare he! I'm going to kill him!_ and _I'll make him regret everything he's ever done,_ was his train of thought._

_The buzzing became a roar._

"You're lying," Jace said. Sebastian shrugged and they were silent as they continued their battle. They were even matched, and their fight dragged on. At some point, Sebastian was pushing Jace back into a wall, and then somehow Jace got the upper hand. Wrestling with Sebastian, Jace threw him on the ground and held him down with his foot. Jace raised his seraph blade -

"Kill me and you kill yourself," Sebastian hissed at him. Jace wondered why he didn't try to move the other's foot - perhaps he was giving up? Or maybe he knew what Jace knew, that Sebastian was right, that this fight was destined to have no winner.

"I've died before," Jace replyed coldly, adopting an indifferent expression. Sebastian chuckled, seeing through the facade.

"Yeah, and so have I. But Clary hasn't. And if you die -" Sebastian leaned up a bit to emphasize his next point - "she might as well. You think she can survive without you? She's strong, and she might recover - but do you want to give her a reason to have to?"

Jace couldn't come up with an answer. He realized he had never hated his brother as much as now, because he knew he was right. The most he could was rough Sebastian up, make him bleed but in the end Jace would always come back, and when their wounds healed, Sebastian would turn back into Jonathon, and Clary would always be in the middle. Like her brother said, she belonged to both of them, and neither was going to give her up.

Jonathon was right.

And Jace cursed him for it.

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><p><strong>A.N-Finally, <em>Valentine's Brood <em>is finished! This wasn't how I pictured it going when I wrote the first chapter, but then ideas started forming for another one-shot, and so I decided to combine them. Now, about the mess with Clary and Sebastian/Jonathon: I know all Sebastian did was kiss her, but I think that idea that Sebastian would do that, and hold her down, combined with the brother/sister factor, just freaked Clary out too much, and that's why she kind of broke down a little.**

**I'm not good at fight scenes, and I knew I couldn't have one of them die - that just isn't real. So I was racking my brain for a way to end this chapter, and I hope I ended it on a good note. Throughout this whole story, I tried to make the characters' thinking sporadic, with short bursts of flow. I wanted it messy, but clean enough that it sill seemed like poetry. I also tried to incorporate quotes or teasers from the TMI and TID series into this, because I think it makes it more special **


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